This core will support the projects proposed herein by the expansion and maintenance of the high risk cohort of uninfected men and women, the development of an outreach program to recruit additional subjects with acute or early HIV infection, and facilitation of data collection across multiple sites. This Core will also extend the functions of the NYU CFAR Clinical Support Core in the provision of biostatistical and epidemiological analyses for all projects. The Core will identify persons with acute and early HIV infection to support the timely completion of each of the projects. Epidemiologic information will be accumulated on each subject to estimate the date and route of HIV infection, demographic characteristics, and information when possible on the individual from whom infection was acquired in order to obtain information on natural history. Subjects with acute and early HIV infection will be referred for enrollment into the proposed clinical trial, and for intensive immunologic and virologic studies as proposed, whether or not they elect to be treated. The Core will provide data management services for each of the participating projects; create methods for the rapid transmission of data to the Core, and establish, in conjunction with FSTRF, a common data base for the program project. This will facilitate analysis of associations between the observations collected by the collaborating investigators. Core staff will program the audio computer assisted interviewing system to be used for collection of demographic and behavioral information from cohort participants in English and French. The Core will assist in the development and review of new projects emerging from the program project and will provide biostatistical and epidemiological expertise for these proposals.